1. Field of the Invention
This invention concerns a magnetic head device provided with a magnetoresistance effect-type thin film magnetic head element for reproduction, and the method for its manufacture.
2. Background Information
The magnetic head devices present in hard disk devices and other equipment are provided with a thin film magnetic head element on the trailing-side surface of a slider mounted on a suspension. The magnetic gap of the magnetic head element is exposed on a surface of the slider facing the media (called the air bearing surface or “ABS”) opposing the magnetic recording media. The magnetic head devices are used to perform magnetic recording of information onto and reproduction from magnetic disks or other magnetic recording media.
Trends toward higher recording densities in recent years have been accompanied by the widespread adoption of thin film magnetic head elements. Thin film magnetic head elements are integrated by layering a magnetoresistance head. A magnetoresistance effect element is used as a magnetic reproduction element part for readout of information recorded onto magnetic recording media and an induction-type magnetic head (inductive head) is used for recording.
The construction of the aforementioned magnetic head device has conventionally relied on the following processes. First, numerous thin film magnetic head elements, comprised of multiple layers fabricated using vacuum thin film fabrication techniques, are formed in a lattice array on top of a disc-shaped wafer comprised of an AlTiC substrate (Al2O3-TiC substrate). Next, the wafer is cut to separate each head block. Then, by performing the desired machining and other processing for a head block, a slider is constructed.
In the aforementioned magnetic head device, the aforementioned cut surface becomes the ABS (air bearing surface) of the slider. Because high precision is required in the machining of this ABS in order to improve the contact start-stop (“CSS”) durability and other characteristics, a polishing jig is used for polishing after the aforementioned cutting, in order to flatten the ABS, and in order that the stripe height (SH) of the magnetoresistance effect element is the desired value.
Because the aforementioned polishing process consists of mechanical surface polishing, a large stress acts on the surface layer part of the polished ABS, and because of machining strain induced by the stresses and similar causes, the magnetic properties of the surface layer part are changed, and a magnetically degenerated layer is formed.
The magnetically degenerated layer is an extremely thin layer, of thickness approximately 1000 Å. However, due to the narrowing of the stripe heights of magnetoresistance effect elements with still greater increases in areal recording densities in recent years, the degradation of the output characteristic resulting from the existence of a the magnetically degenerated layer is becoming too great to be ignored.
Hence an objective of this invention is to alleviate the degradation of the output characteristics arising from mechanical polishing of the ABS of the slider in magnetoresistance effect-type magnetic head devices.